Electronic image sensors are widely used to produce video and photographic images. The electronic image sensors typically comprise pixel sensors that are arranged in an array of rows and columns. The image sensors typically read pixel values by using a horizontal scan circuit to sequentially address pixel columns. A charge amplifier is often used to read the charge of pixels within the addressed pixel columns.
As pixel pitches decrease, charge diffusion crosstalk increases. The crosstalk between neighboring pixels causes color-shifting problems in the image captured by the electronic sensor. Color-shifting occurs when monochromatic light (e.g., red, green, or blue) is shifted from its true color a result of the addition of diffused charge from neighboring pixels of different colors. The effect of color-shifting increases as pixel pitch decreases. Crosstalk is a function of doping concentration, charge free running distance and layout structure. For small pixels (e.g., 3.2 um pitch pixel with 0.18 um advanced CMOS processing), crosstalk of red light can be as high as 20%, which can cause very noticeable color-shifting in a captured image.
An appreciation of the present invention and its improvements can be obtained by reference to the accompanying drawings, which are briefly summarized below, to the following detailed description of illustrated embodiments of the invention, and to the appended claims.